I am going to leave the part numbers here (PF3SBP-12 Part # 23170-21 with RFU-25 Rudder
Feedback Unit) for easy searching, but I am guessing this applies to almost any pumpset. The specific pumpset I am talking about is made by AutoNav and works together with a Nexus autopilot
The fluid in the pumpset looked darkish with some residue, and there was very little of it in the reservoir, so I decided I needed to change it.
At first I drained the old fluid. This was relatively easy. just unscrewed these hoses:
The only trick was to drain the reservoir below the intake line. I had to unscrew the pump
to be able to lay it on the side to drain all residue from the reservoir.
Then the question was: what do I put back into the system. A few people suggested ATF (automatic transmission
fluid) for its good de-greasing qualities, so that's what I did.
Now I had to drain the air from the system, so I followed the instruction manual and steered the system from extreme right to extreme left several times by using the "power steering" mode on the auto pilot. This presented a bit of a problem. Air compresses well, so when I reversed direction, the ATF gushed out of the reservoir. Eventually I figured to do it in small increments, and was able to drain all air from the system.
At the moment, even though my system is calibrated so that 0 on the instrument corresponds to the 0 degrees rudder
, when I steer to extreme port using power steering
- it only goes to like 36 degrees, and if I go to extreme starboard, it goes to 45 and doesn't stop there (the motor
continues to pump) even though the rudder has reached its limit in turning point. This causes pressure to build up, and when I reverse direction, the pump
set spits out the ATF from the reservoir.
I believe this has to do with how the RFU was installed. Should I adjust it and re-calibrate in order to balance port and starboard extreme points? Has anyone had a similar problem? how did you solve it?